Figure 4.

Dumbbell nanomaterials. (A) Schematic illustration of the synthesis of Au-Fe₃O₄ dumbbell NPs. (B) Representative transmission electron micrograph and (C) high-resolution image of the formed Au-Fe₃O₄ dumbbell NPs. (D) Schematic illustration of the Au₂ overgrowth on Au₁ NP and Au₁ NP detachment from the Fe₃O₄ NP, forming the new dumbbell-like Au₁-Au₂ and the dented Fe₃O₄ NP. (E) Transmission electron micrograph of the prepared Au₂-Au₁-Fe₃O₄ NPs. Reprinted with permission from (75). Copyright 2005 American Chemical Society. Reprinted with permission from (76). Copyright 2009 American Chemical Society.